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Areal Extent of Sediment Overburden in Restored Prairie Wetlands and the Impact on Recolonization by Aquatic Invertebrates and Hydrophytes in the United States Prairie Pothole Region.

Study Area and Sampling Design

The study area includes portions of Montana, North Dakota, South Dakota, Minnesota, and Iowa. NPWRC's sampling design consisted of stratifying the PPR into three physiographic regions: Missouri Coteau, Prairie Coteau, and Glaciated Plains. A random-systematic sampling design was used to place 9 sampling points in the Missouri Coteau, 3 in the Prairie Coteau, and 12 in the Glaciated Plain (Figure 1). Near each sampling point, seasonal and semipermanent wetlands were selected from the following categories.

  1. Restored wetlands 1-5 years old: Wetlands in CRP habitats or similar grasslands restored for 1-5 years. CRP type habitats were once farmed lands currently planted back to perennial grassland cover.
  2. Restored wetlands >5-10 years old: Wetlands in CRP habitats restored for >5-10 years.
  3. Drained wetland: Ditch or tile drained wetlands in CRP habitats that are similar to restored wetlands with respect to land-use history, wetland area, catchment area, and soils.
  4. CRP wetland: Nondrained wetlands (i.e., natural wetland) in CRP habitats that are similar to restored wetlands with respect to land-use history, wetland area, catchment area, and soils.
  5. Pristine wetland: Pristine wetlands are nondrained wetlands (i.e., natural wetland) in nontilled (i.e., never tilled) grasslands. This may include grazed, hayland, and idle native prairie habitats. Hence, land-use history of pristine wetlands will differ from the other 4 categories, but are similar with respect to wetland area, catchment area, and soils.

GIF -- Location of wetland sample areas.
Figure 1. Location of wetland sample areas in the Missouri Coteau (MC 1-9), Prairie Coteau (PC 1-3), and Glaciated Plains (GP 1-12).

The extensive survey performed by NPWRC resulted in the sampling of 204 wetlands (Appendix A). Detailed information on wetland selection criteria and sampling design are described in the extensive survey Study Plan 168.01 (NPWRC 1997a).

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